I said:
> Try this. You'll also need to change "ThingCompare a" to "ThingCompare"
> in all your function type signatures.
>> > data ThingCompare
> > = forall a. TC (BooleanOp a) (Field a)
> > | And ThingCompare ThingCompare
> > | Or ThingCompare ThingCompare
>
Sorry. For that to work, you would need "-fglasgow-exts", which presumes
you are using GHC. I just noticed from your post that you are using
Hugs.